Sensor device particularly for maritime applications

ABSTRACT

The invention relates to a sensor device particularly for maritime applications, comprising a housing ( 1 ) that has a pressure connection ( 7 ) leading to a pressure sensor ( 9 ) that transmits measurement data using a transmission device ( 17, 19 ), and at least one closeable passage opening ( 31 ) for connecting the surroundings to at least parts ( 33 ) of the housing interior in which the pressure sensor ( 9 ) is arranged, characterised in that said pressure sensor ( 9 ) is surrounded by an incompressible medium that is separated from the surroundings by an elastically-yielding, media-tight separating arrangement ( 49 ).

The invention relates to a sensor device, particularly for maritime applications, having a housing that has a pressure connection leading to a pressure sensor that transmits measurement data by means of a transmission device, and that has at least one connectable passage opening for connecting the surroundings to at least parts of the housing interior in which the pressure sensor is arranged. The invention furthermore relates to the use of such a pressure sensor device in deep water applications. In deep water applications such as hydraulic function units (BOP) or ROV (remote operated vehicles), sensors, valves, etc. are placed in an oil-filled chamber, which is adjusted to ocean pressure level by compensators (compensated chamber).

Sensor devices having pressure sensors for measuring media pressures are prior art, see for example DE 102 12 767 A1. In particular, such devices are used for monitoring the system pressure in systems that use pressurized fluids as working media. In an encapsulated system, the ambient pressure adds up to the system pressure, which gives rise to the difficulty that in the case of high ambient pressures, the pressure sensor must be designed for a potentially very high pressure level, even though a much lower system pressure relative to the ambient pressure is to be monitored and accordingly only a small portion of the measurement range can be used. For solving this problem, according to the prior art the sensor housing is brought to ambient pressure so that the pressure sensor is pressurized with the ambient pressure on the one hand and with the system pressure on the other hand and as a result only measures the system pressure. In the case of sensor devices that are exposed to atmospheric pressure, the procedure is such that the pressure compensation between outside air and air present in the sensor housing is effected via a gas-permeable pressure compensation diaphragm. Such venting diaphragms are known as pressure compensation diaphragms, and they are commercially available in the form of hydrophobic-oleophobic PTFE diaphragms. For applications in which the sensor device is situated under water, this procedure is not feasible because air or nitrogen gas in the housing is compressible and the diaphragm is not sufficiently supported, hence high differential pressures on the diaphragm lead to water penetrating the housing and damaging the electronics associated with the sensor.

With respect to these problems, the invention is based on the object of providing a sensor device of the aforementioned generic type that permits reliable use in the case of ambient fluid pressure, for example sea water pressure in a so-called compensated chamber (oil-filled hydraulic chamber adjusted to ocean pressure). According to the invention, this object is achieved by a sensor device that has the features of claim 1 in its entirety.

According to the characterizing part of claim 1, an essential feature of the invention is that the pressure sensor is surrounded by a largely incompressible medium, which is separated from the surroundings by an elastically yielding, media-tight separating mechanism. An oil such as silicone oil or transformer oil, or other incompressible material in the form of, e.g., a gel or a potting material, is advantageously provided as an incompressible medium with which a chamber containing the pressure sensor in the housing is filled, which chamber is sealed off with respect to the surroundings by the flexible, media-tight separating mechanism. The sensor device according to the invention can thus also be used in a reliable manner for deep water applications such as blow-out preventers or ROVs, e.g., on the ocean floor at a depth of ca. 4000 meters with an ambient pressure of 400 bar or more.

The transmission device can have a circuit board to which the pressure sensor is connected, as well as connection cables with which the circuit board can be hooked up to an analysis device. Alternatively, provision can also be made for wireless radio transmission.

In particularly advantageous exemplary embodiments, the separating mechanism is configured in the nature of a rolling diaphragm of which, folded over at a deflection point, a cup-like inner part engages in a pot-like widening of a receiving part, at least in the initial state of the diaphragm. An elastomer such as a nitrile butadiene rubber can be advantageously provided as a material for the rolling diaphragm.

With particular advantage, it can be arranged such that the separating mechanism configured as an elastically yielding diaphragm is fixed by its free edge in a receiving chamber of the tubular receiving part, which chamber is constantly exposed to the ambient pressure. The pot-like receiving part for the diaphragm can be arranged centrally in and passing through a partition of the housing, wherein the partition has at least one passage opening that can preferably be closed with a sealing screw.

Connection cables of the transmission device for the measurement data obtained by the pressure sensor can pass through this partition.

In particularly advantageous exemplary embodiments, another housing part, which is continuously connected to the surroundings, preferably via at least one passage opening, and which opens in the free end of the receiving chamber of the receiving part, adjoins the partition of the housing that seals off the housing interior towards the pressure sensor by means of the particular sealing screw.

This receiving part for the diaphragm can be designed as a screw-in part and can be sealingly screwed into the partition. Furthermore, the pressure sensor and the circuit board can be held in a receiving bracket or receiving basket in the housing.

According to claim 10, the subject matter of the invention is also the use of a pressure sensor device according to any one of claims 1-9 in deep water applications, particularly in blow-out preventers, said device having a pressure sensor, which for measuring a system pressure is received in a housing with an incompressible medium, which during use is exposed to the prevailing ambient water pressure by means of an elastically yielding separating mechanism.

The invention is explained in detail below, with reference to an exemplary embodiment illustrated in the drawings, wherein:

FIG. 1 shows a cutaway, longitudinal sectional view of a pressure sensor device according to the prior art;

FIG. 2 is an illustration of an exemplary embodiment of the sensor device according to the invention, cut open in the longitudinal direction; and

FIG. 3 shows a perspective oblique view of the exemplary embodiment of FIG. 2.

FIG. 1 shows a prior art sensor device having a metal sensor housing 1, which has a circular-cylindrical main part 3, of which the lower end in FIG. 1 is sealed off by a welded-on bottom part 5. This bottom part 5 has a centrally located pressure connection 7, via which one side of the pressure measuring cell of a pressure sensor 9, which is arranged on the bottom part 5, can be subjected to the system pressure to be measured. The upper, opposite end of the housing main part 3 is closed in a fluid-tight manner by means of a screw cap 10. A pressure-compensating bore 11, which is closed by means of a standard gas-permeable venting diaphragm 13, is located in the wall of the housing main part 3. This diaphragm can be a standard pressure compensation diaphragm made of PTFE, which is applied in a self-adhesive manner to the inner wall of the housing main part 3.

As a result of the pressure compensation via the bore 11, the air or optionally other gaseous medium such as nitrogen gas situated in the housing interior 15 is under ambient pressure so that the pressure measuring cell of the pressure sensor 9, which is exposed to the system pressure by the pressure connection 7 on the one hand and subjected to the ambient pressure on the other hand and thus only detects the system pressure as a pressure differential relative to the ambient pressure. The pressure sensor 9 is connected to a circuit board 17, from which connection cables 19 lead to a connector plug unit 21, which is in turn connected to an electronic analyzer 23. The plug unit 21 is arranged on the cap 10, in the center thereof. For holding the circuit board 17, provision is made of a receiving basket 25, which is secured on the inside of the bottom part 5.

FIGS. 2 and 3 show an exemplary embodiment of the sensor device according to the invention. As is the case with the prior art device shown in FIG. 1, the sensor housing 1 has a circular-cylindrical main part 3, which is closed at the lower end in the drawing by a welded-on bottom part 5, on which a pressure connection 7 for the pressurized fluid, the system pressure of which is to be measured, is provided and connected to one side of the measuring cell of the pressure sensor 9, which is arranged together with a retaining basket 25 for the circuit board 17 on the bottom part 5. A third metal housing part in the form of a partition 29, which is welded to the housing main part 3 and the housing part 27, is located between the upper end of the main part 3 and a metal housing part 27 forming the upper housing cover. The interior space 33 of the end-side housing part 27 is continuously connected to the surroundings via passage openings 31.

As in the case of the cover cap 10 of the solution shown in FIG. 1, the wall of the housing part 27 having the passage openings 31 has a plug unit 21 that is connected to the circuit board 17 via connection cables 19. The cables 19 are sealingly guided through the partition 29.

Situated in the partition 29 and coaxially to the longitudinal axis of the housing is a threaded through-bore 35, into which a tubular receiving part 37 is screwed in such a way that its upper, open end 39 is in connection with the ambient pressure-conducting interior space 33 of the upper housing part 37 so that the receiving part 37 forms a receiving chamber 41 in the interior that is continuously exposed to the ambient pressure. On the end opposite the upper end 39, this receiving chamber has a pot-like widening 43, on which is formed a radial outer shoulder 45, which rests on the partition 29 and is sealed there by means of a gasket 47 when the receiving part 37 is screwed into the partition 29. A rolling diaphragm 49 is arranged in the pot-like widening 43 and secured in such a way that the free edge 51 of the rolling diaphragm 49 is securely clamped on an inner shoulder 53 at the opening region of the receiving part 37 by means of a press-fit locking ring 55. By means of the rolling diaphragm 49 that forms a movable separator element, the ambient pressure-conducting interior space 33 in the housing part 27 is separated in a fluid-tight manner from the interior space 15 having the pressure sensor 9 and located in the housing main part 3.

In the partition 29, provision is made of passage openings 57, which can be closed in a fluid tight manner by means of sealing screws 59. The housing interior space 15 is filled via the passage openings 57 with an incompressible medium, in the case of the exemplary embodiment with an oil that is compatible with the electronics of the circuit board 17 such as silicone oil or transformer oil, the chamber pressure of which pressurizes the measuring cell of the pressure sensor 9 on the side opposite the side subjected to the system pressure and connected to the pressure connection 7. Because the rolling diaphragm 49 forms a movable, flexible separator element between the ambient pressure-conducting space 33 and the interior space 15 containing the pressure sensor 9, it transfers the ambient pressure to the chamber pressure of the space 15. Because the incompressible fill of the space 15 forms a rigid support for the rolling diaphragm 49, which extends from its secured edge 51 along the inner wall of the pot-like widening 43 of the receiving part 37 into the tapered part of the receiving chamber 41 of said receiving part, where the rolling diaphragm 49, starting from a deflection point 61 and forming a type of cup 63, extends towards the interior space 15, the rolling diaphragm 49 forms a reliable separation point, which due to its flexibility equalizes the ambient pressure prevailing in the chamber 33 with the chamber pressure acting on the pressure sensor 9 in the interior space 15. Because the rolling diaphragm 49 extends with a cup 63 into the interior space 15, a volume compensation can be achieved by a diaphragm movement that changes the length of the cup 23, which in turn changes the volume of the interior space 15, thereby ensuring that a possible filling level deficit of the incompressible medium in the space 15 can be compensated and that the rolling diaphragm 49 is thus rigidly supported in a reliable manner. As mentioned, for the fluid-tight separation an elastomer such as nitrile butadiene rubber can advantageously be provided as a material for the rolling diaphragm 49. 

1. A sensor device, in particular for maritime applications, having a housing (1) that has a pressure connection (7) leading to a pressure sensor (9) that transmits measurement data by means of a transmission device (17, 19), and at least one closeable passage opening (31) for connecting the surroundings to at least parts (33) of the housing interior in which the pressure sensor (9) is arranged, characterized in that the pressure sensor (9) is surrounded by an incompressible medium that is separated from the surroundings by means of an elastically yielding, media-tight separating mechanism (49).
 2. The sensor device according to claim 1, characterized in that the transmission device has a circuit board (17) to which the pressure sensor (9) is hooked up, as well as connection cables (19) with which the circuit board (17) can be hooked up to an analyzer device (23).
 3. The sensor device according to claim 1 or 2, characterized in that the separating mechanism is configured in the fashion of a rolling diaphragm (49), of which a cup-like interior part (63), folded over on a deflection point (61), engages in a pot-like widening (43) of a receiving part (37), at least in the initial state of the diaphragm (49).
 4. The sensor device according to claim 1, characterized in that the separating mechanism configured as an elastically yielding diaphragm (49) is secured by its free edge (51) in a receiving chamber (41) of the tubular receiving part (37), which chamber is continuously exposed to the ambient pressure.
 5. The sensor device according to claim 1, characterized in that the receiving part (37) is arranged centrally in and passes through a partition (29) of the housing (1), and that the partition (29) has at least one passage opening (57) that can preferably be closed with a sealing screw (59).
 6. The sensor device according to claim 1, characterized in that the connection cables (19) of the transmission device (17, 19) pass through the partition (29).
 7. The sensor device according to claim 1, characterized in that another housing part (27), which is continuously connected to the surroundings preferably via at least one passage opening (31) and opens into the free end of the receiving chamber (41) of the receiving part (37), adjoins the partition (29) of the housing (1) that seals off the housing interior (15) towards the pressure sensor (9) by means of the particular sealing screw (59).
 8. The sensor device according to claim 1, characterized in that the receiving part (37) designed as a screw-in part, for example, is sealingly screwed into the partition (29).
 9. The sensor device according to claim 1, characterized in that the pressure sensor (9) and the circuit board (17) are held in a receiving bracket or receiving basket (25) in the housing (1).
 10. A use of a pressure sensor device according to claim 1 for deep water applications, in particular for blow-out preventers, having a pressure sensor (9) which, for measuring a system pressure, is received in a housing (1) with an incompressible medium, which during use is exposed by means of an elastically yielding separating mechanism (49) to the prevailing ambient water pressure in a compensated chamber. 